Trispecific Hybrid Research Articles

Tropical range grasses can sustain soil functions despite nutrient depletion in semiarid degraded land

Soil function encompasses numerous functions and services the soil provides and can be measured using physical, chemical, and biological characteristics. In any event, research on fertility and biological activity is increasingly being stressed as indices of ecosystem services. Rangeland degradation is one of the world's most widespread land use changes, with serious consequences for soil processes and ecosystem services. The influence of uncontrolled grass cover on soil functioning in semiarid environments is little understood. In the current study, the following seven varieties of grass coverings were studied in a semiarid area of central India: Cenchrus ciliaris (CC), Megathyrsus maximus (MM), Chrysopogon fulvus (CF), Heteropogon contortus (HC), Sehima nervosum (SN), Vetiveria zizanioides (VZ), and Tri-Specific Hybrid (TSH). The carbon accumulation proficiency of TSH, MM, and HC was ~2.23, 2.17, and 2.07 times greater than fallow. The nutrient cycling capacity of grasses was ~1.1 to 1.6 times greater than that of fallow, despite the grasses' depleted macronutrients in the soil. The biological activity under MM and HC was ~1.23 and 1.67 times higher than fallow. Overall soil functionality under TSH and HC was 83 and 25% greater than MM, respectively. These soil functions augment ecosystem services like climate regulation, biomass production, nutrient recycling, water, and airflow. However, more attention should be paid to the management of inputs for greater ecosystem services from this grass cover in semiarid, degraded land.

Understanding Soil Carbon and Phosphorus Dynamics under Grass-Legume Intercropping in a Semi-Arid Region

An integrated forage-legume cropping system has immense potential to address the issue of land degradability. It provides a critical understanding of the capacity of diversified species mixes vs. monocultures to boost forage production and the dynamics of soil organic carbon (SOC) and phosphorus (P). In this study, we assessed the performance of Napier Bajra Hybrid (NBH) (Pennisetum glaucum × P. purpureum) + cowpea (Vigna unguiculata) and tri-specific hybrid (TSH) (P. glaucum × P. purpureum × P. squamulatum) + cluster bean (Cyamopsis tetragonoloba) as compared to monocultures of NBH and TSH. The legume equivalent yield of NBH + cowpea and TSH + cluster bean intercropping systems were found −31% and −23% higher than monoculture systems. The SOC increased by −5% in the NBH + cowpea system as compared to NBH monoculture. The carbon mineralization rates under NBH + cowpea and TSH + cluster bean were −32% and −38% lower than the NBH and TSH monoculture cropping systems, respectively. It was found that the legume intensification with the forage significantly improved the soil’s P status. The research suggested that coalescing diverse crops (e.g., grass and legume) poses enormous potential for sustaining soil health and productivity in semi-arid regions of India. This study advances the research on characterizing the crucial factors of grass-legume-based cropping systems and helps in assessing the impact of these factors on long-term sustainability.

Physiological response of Bajra-Napier Hybrids and Tri-Specific Hybrid to salinity stressPhysiological response of Bajra-Napier Hybrids and Tri-Specific Hybrid to salinity stress

Physiological responses of 3 Bajra-Napier (Cenchrus spp., syn. Pennisetum spp.) hybrid varieties, viz. BNH-3, BNH-6, BNH-10, and 1 ttri-specific hybrid (TSH) were tested under different gradients of soil salinity, i.e. Control, 4, 6 and 8 dS/m electric conductivity (EC), in a pot trial. The experiment was laid out in a factorial completely randomized design with 3 replications. Shoot dry weight, root dry weight, root:shoot ratio and chlorophyll a, chlorophyll b, total chlorophyll and carotenoid concentrations were reduced with increasing salinity level as compared with Control. However, the concentration of Na+ in leaves increased and K+ concentration decreased with increasing salinity level. Physiological parameters, i.e. relative water content (RWC), membrane stability index (MSI), chlorophyll stability index, carotenoid stability index and K+: Na+ ratio, in leaves tended to be higher in the BNH-3 variety than in other varieties. Shoot dry weight showed highly positive significant correlation with RWC, MSI, K+ concentration and K+:Na+ ratio, while it was negatively correlated with Na+ concentration (P<0.01) All BN hybrid varieties and the tri-specific hybrid studied were susceptible to salinity stress, showing marked reductions in growth as the level of salinity increased above 4 dS/m. However, even at salinity levels producing EC of 8 dS/m these varieties still produced 25‒44% DM yields. There are prospects for improving forage yields from saline soils by planting these hybrids but further breeding studies are warranted to identify germplasm with greater tolerance of saline conditions if these soils are to be utilized effectively to contribute more to supplying forage to support the world’s ruminant population.

Effect of Food-fodder Farming on Sustainable Resources Use and Carbon Dynamics in Rainfed Semi-arid Tropics of India

ABSTRACT Soil organic carbon (SOC) is highly sensitive to land use change and helps in maintaining soil quality. Changes in soil fertility status, SOC dynamics, and carbon indices were studied in a four-year experiment with nine sets of food-fodder cropping systems (CS) and three resource conservation techniques like rainfed (RC1), life saving irrigation (RC2) and in-situ moisture conservation practices (RC3). Results showed that the CS5 [Tri-Specific Hybrid (TSH) + Desmanthus virgatus+ (Sorghum + Cowpea – Chickpea)] recorded the highest values 12.25 g kg−1, 41.5 mg kg−1, 3.5 g kg−1, 289.5 mg kg−1, 424.8 µg g−1 soil, 54.69% and 39.31% of total carbon (TC), hot water-soluble carbon (HWSC), particulate organic carbon (POC), labile carbon (LC), soil microbial biomass carbon (SMBC), humic acid carbon (HA-C) and fulvic acid carbon (FA-C), respectively. Among resources conservation practices, RC3 improved the SOC (56.16%) and other carbon fractions significantly as compared to RC1. Significant and positive correlations (P < 0.05) were found between carbon pools and available nutrients. The carbon management index (CMI) was also maximum (193) with CS5 and CS9 [TSH + Sesbania sesban+ (Sorghum + Cowpea – Barley)] and RC3 (232). Therefore, promoting cultivation of food-fodder system with in-situ moisture conservation practices is considered as sustainable management option for sequester more carbon, sustainability and soil quality in rainfed semi-arid ecosystem.

Tripsazea, a Novel Trihybrid of Zea mays, Tripsacum dactyloides, and Zeaperennis.

A trispecific hybrid, MTP (hereafter called tripsazea), was developed from intergeneric crosses involving tetraploid Zea mays (2n = 4x = 40, genome: MMMM), tetraploid Tripsacum dactyloides (2n = 4x = 72, TTTT), and tetraploid Z. perennis (2n = 4x = 40, PPPP). On crossing maize-Tripsacum (2n = 4x = 56, MMTT) with Z. perennis, 37 progenies with varying chromosome numbers (36-74) were obtained, and a special one (i.e., tripsazea) possessing 2n = 74 chromosomes was generated. Tripsazea is perennial and expresses phenotypic characteristics affected by its progenitor parent. Flow cytometry analysis of tripsazea and its parents showed that tripsazea underwent DNA sequence elimination during allohexaploidization. Of all the chromosomes in diakinesis I, 18.42% participated in heterogenetic pairing, including 16.43% between the M- and P-genomes, 1.59% between the M- and T-genomes, and 0.39% in T- and P-genome pairing. Tripsazea is male sterile and partly female fertile. In comparison with previously synthesized trihybrids containing maize, Tripsacum and teosinte, tripsazea has a higher chromosome number, higher seed setting rate, and vegetative propagation ability of stand and stem. However, few trihybrids possess these valuable traits at the same time. The potential of tripsazea is discussed with respect to the deployment of the genetic bridge for maize improvement and forage breeding.

Production of New Cotton Interspecific Hybrids with Enhanced Fiber Fineness

&lt;p&gt;To improve cotton fiber fineness, the (&lt;em&gt;Gossypium hirsutum&lt;/em&gt; L. × &lt;em&gt;Gossypium longicalyx &lt;/em&gt;Hutch. &amp;amp; Lee)² allohexaploid and the [(&lt;em&gt;Gossypium hirsutum&lt;/em&gt; L. × &lt;em&gt;Gossypium thurberi &lt;/em&gt;Tod.)² × &lt;em&gt;G. longicalyx&lt;/em&gt;] allotetraploid were backcrossed to &lt;em&gt;G. hirsutum&lt;/em&gt; to produce introgressed genetic stocks. The ribbon width (RW) of 600 swelled fibers produced by the hybrids, their parents, and their backcross progeny were analyzed for each compared genotype using an optical microscope. The RWs varied between 6.41±2.15 µm for &lt;em&gt;G. longicalyx&lt;/em&gt; to 17.45±2.98 µm for the &lt;em&gt;G. hirsutum&lt;/em&gt; parent cultivar C2. Fibers produced by the trispecific hybrids and their progeny were finer than the bispecific hybrid material. For the introgressed stocks, the lowest RWs were observed for the trispecific hybrid (10.79±2.14 µm) and certain backcross progenies (between 11.98±1.27 µm to 12.71±1.61 µm). The allohexaploid RW was 13.58±1.41 µm. One of its tetraploid progeny produced approximately the same value (13.94±2.48 µm). These results show that &lt;em&gt;G. longicalyx &lt;/em&gt;is a potential genetic stock for cotton fiber fineness improvement. The genetic stocks produced are valuable materials for improve the fineness of cotton fiber.&lt;/p&gt;

Plant-herbivore interactions in a trispecific hybrid swarm of Populus: assessing support for hypotheses of hybrid bridges, evolutionary novelty and genetic similarity.

Natural systems of hybridizing plants are powerful tools with which to assess evolutionary processes between parental species and their associated arthropods. Here we report on these processes in a trispecific hybrid swarm of Populus trees. Using field observations, common garden experiments and genetic markers, we tested the hypothesis that genetic similarities among hosts underlie the distributions of 10 species of gall-forming arthropods and their ability to adapt to new host genotypes. the degree of genetic relatedness among parental species determines whether hybridization is primarily bidirectional or unidirectional; host genotype and genetic similarity strongly affect the distributions of gall-forming species, individually and as a community. These effects were detected observationally in the wild and experimentally in common gardens; correlations between the diversity of host genotypes and their associated arthropods identify hybrid zones as centres of biodiversity and potential species interactions with important ecological and evolutionary consequences. These findings support both hybrid bridge and evolutionary novelty hypotheses. However, the lack of parallel genetic studies on gall-forming arthropods limits our ability to define the host of origin with their subsequent shift to other host species or their evolution on hybrids as their final destination.

Analysis of [Gossypium capitis-viridis × (G.hirsutum × G.australe)2] Trispecific Hybrid and Selected Characteristics.

Speciation is always a contentious and challenging issue following with the presence of gene flow. In Gossypium, there are many valuable resources and wild diploid cotton especially C and B genome species possess some excellent traits which cultivated cotton always lacks. In order to explore character transferring rule from wild cotton to upland tetraploid cotton, the [G. capitis-viridis × (G. hirsutum × G. australe)2] triple hybrid was synthesized by interspecies hybridization and chromosome doubling. Morphology comparisons were measured among this hybrid and its parents. It showed that trispecific hybrid F1 had some intermediate morphological characters like leaf style between its parents and some different characters from its parents, like crawl growth characteristics and two kind flower color. It is highly resistant to insects comparing with other cotton species by four year field investigation. By cytogenetic analysis, triple hybrid was further confirmed by meiosis behavior of pollen mother cells. Comparing with regular meiosis of its three parents, it was distinguished by the occurrence of polyads with various numbers of unbalanced microspores and finally generating various abnormal pollen grains. All this phenomenon results in the sterility of this hybrid. This hybrid was further identified by SSR marker from DNA molecular level. It showed that 98 selected polymorphism primers amplified effective bands in this hybrids and its parents. The genetic proportion of three parents in this hybrid is 47.8% from G. hirsutum, 14.3% from G. australe, 7.0% from G. capitis-viridis, and 30.9% recombination bands respectively. It was testified that wild genetic material has been transferred into cultivated cotton and this new germplasm can be incorporated into cotton breeding program.

Evaluation of Seven Complex Pennisetum Hybrids for Container and Landscape Performance in the Pacific Northwestern United States

Ornamental grasses such as fountaingrass or napiergrass, collectively called pennisetums, belong to the genus Pennisetum, which is a diverse genus with over 80 species adapted to a wide range of climatic regions and known for its drought tolerance. Breeding efforts have led to improvements such as more intense purple foliage color, disease resistance, and apparent sterility. These improved forms have been developed and tested in the eastern United States. The objective of this research was to evaluate container and field performance of seven new complex hybrid pennisetums in the Pacific northwestern United States. Two completely randomized experiments with three replications were conducted over 2 years (2010 and 2011) at two locations. We selected seven trispecific hybrid pennisetums resulting from interploid and interspecific crossing that were given accessions Tift 5, Tift 6, Tift 10, Tift 11, Tift, 13, Tift 15, and Tift 26. Experiment 1 evaluated container performance in Corvallis, OR, while Expt. 2 evaluated field performance in Aurora, OR. Size index (SI), growth form rating, and color rating were collected and analyzed separately by location. In the container study, significant differences were observed among selections for growth form in 2010 and color ratings in both 2010 and 2011. In 2010, Tift 6, Tift 11, Tift 13, and Tift 15 had the highest growth form rating. For color rating, Tift 5, Tift 10, and Tift 26 were among the four highest rated selections in both years. In the field study, Tift 5, Tift 10, Tift 11, and Tift 26 had the highest SI when data were pooled over the 2 years, but all selections reached acceptable size for landscape use during both years of the study. Similarly, there were color differences among selections with Tift 5, Tift 10, Tift 15, and Tift 26 being highest rated. None of the selections survived below winter temperatures of −5 °C at either location during either year of the study. Our evaluations indicate that these selections have potential in the Pacific northwestern United States as annuals. Differences in complex hybrid pennisetums were observed in SI, growth form rating, and color rating. These differences demonstrated the variation among selections and will allow producers to choose desired traits based on market preference.

陆地棉、澳洲棉和绿顶棉三元杂种的细胞遗传学研究

棉属有丰富的种质资源，野生棉具有栽培种所缺乏的许多优良性状，为了将野生澳洲棉和绿顶棉的优良性状导入陆地棉，以期改良栽培种陆地棉。本研究通过陆地棉和C组野生澳洲棉远缘杂交获得杂种F1，并对其进行染色体加倍，将加倍成的异源六倍体与B组野生绿顶棉杂交，产生陆地棉、澳洲棉、绿顶棉的三元杂种，并对该三元杂种花粉母细胞减数分裂行为进行观察。结果表明：三元杂种减数分裂异常，主要表现在：后期染色体不均等分离，使得末期形成大量的不正常多分孢子，其中以五分体居多，这些多分孢子进一步发育为大量败育花粉粒，导致该杂种高度不育。本研究不仅为该三元杂种不育提供了直接原因，也为进一步探讨有效的育性恢复方法及棉花新种质的创制提供了理论依据和中间材料。 There are rich germplasm resources in Gossypium and wild cotton species possess many valuable agronomic traits which cultivated cotton always lacks. In order to introgress the useful traits from wild species G. australe and G. capitis-viridis into cultivated species for improving upland cotton, tetraploid G. hirsutum was crossed directly with C-genome species G. australe as the pollen-providing parent, creating a triploid hybrid. Chromosome doubling of this triploid hybrid leads to an allohexaploid which was then crossed with B-genome wild species G. capitis-viridis, resulting in trispecific hybrid (G. hirsutum, G. australe and G. capitis-viridis). The characteristic of chromosome behavior during meiosis of trispecific hybrid F1 was further investigated in this study. Results indicated that the meiosis of trispecific hybrid was abnormal, which mainly reflected that the chromosomes were divided unequally during the anaphase II; and many abnormal multispores appeared in the telophase II, which finally developed into abortive pollen grains, directly leading to the sterility of trispecific hybrid F1. This study provides the main reason of sterility for this hybrid and supplies the theory basis and the effective method for restoring the fertility and further creating new cotton intermediate germplasms.

Registration of ‘Tift 8’ Trispecific Ornamental Pennisetum

‘Tift 8’ (Reg. No. CV‐259, PI 659801) is a trispecific ornamental hybrid of Pennisetum approved for release by the University of Georgia College of Agricultural and Environmental Sciences in 2010. It was produced from crosses between P. purpureum Schumach; P. squamulatum Fresen.; and P. glaucum (L.) R. Br. This trispecific hybrid is both pollen and seed sterile. Tift 8 is a vegetatively propagated cultivar that is perennial in USDA hardiness zones 8–10. It can be grown as a vigorous annual in more northern zones. Tift 8 is morphologically similar to ‘Tift 17’, but it is significantly taller and has a significantly smaller culm‐leaf angle than Tift 17. Tift 8 is significantly more resistant to Helminthosporium leaf spot (caused by Helminthosporium ocellum Faris) than ‘Princess’. Mature leaves of Tift 8 have a reddish‐purple color. The plant color of Tift 8 is equal to, and in some tests better than, that of Tift 17. Tift 8 flowers under short days; therefore, it will not produce inflorescences where winter temperatures reach freezing (0°C) or below, or before the daylength is 10.5 h. A plant patent application has been submitted for Tift 8.

Introgression of the low-gossypol seed &amp; high-gossypol plant trait in upland cotton: Analysis of [(Gossypium hirsutum × G. raimondii)² × G. sturtianum] trispecific hybrid and selected derivatives using mapped SSRs

In order to select genotypes of Gossypium hirsutum genetically balanced and expressing the low-gossypol seed & high-gossypol plant trait introgressed from the Australian wild diploid species G. sturtianum, the [(G. hirsutum × G. raimondii)² × G. sturtianum] triple hybrid was backcrossed to G. hirsutum and autopollinated to produce backcross and selfed progenies. Two hundred and six mapped SSR markers of G. hirsutum were used to monitor the introgression of SSR alleles specific to G. sturtianum and G. raimondii in the selected progenies. A high level of heterozygosity, varying from 25 to 100%, was observed for all G. sturtianum-specific SSR markers conserved in the most advanced progenies. These results indicate the existence of segregation distortion factors that are associated with the genes controlling the researched trait. This study represents a starting point to map the genes involved in the expression of the trait and better understand its genetic determinism.

Introgression of a gene for delayed pigment gland morphogenesis from Gossypium bickii into upland cotton

The presence of gossypol and its derivatives above the WHO/FAO standards (0.02–0.04%) in cotton seed oil and meal limits its usage as food and feed. To the contrary, the presence of pigment glands filled with gossypol and its derivatives helps to protect cotton plants from phytophageous pests. Thus a desirable cultivar would have glandless seeds on a glanded plant. This paper describes results on the successful introgression of this trait from Gossypium bickii into cultivated upland cotton. Five different tri-specific hybrids (ABH1, ABH2, ABH3, ABH4 and ABH5) were obtained by crossing the amphidiploid F1 (G. arboreum × G. bickii) with different gland genotypes of G. hirsutum as male parent. The hybrids were highly sterile, and their chromosome configuration at meiosis metaphase 1 (M1) in pollen mother cell (PMC) was 2n = 52 = 41.04 I + 4.54 II + 0.57 III + 0.04 IV. All five hybrids were similar in morphological characters, except for the gland expression and gossypol contents. The hybrid (ABH3) derived from genotype Gl2Gl2gl3gl3 of upland cotton (a single gene dominant line) had completely introgressed the target trait of G. bickii. While ABH1 and ABH2, which derived from recessive (gl2gl2gl3gl3) or dominant (GlGl) glandless upland cotton genotypes, had glandless seeds too, but the density and size of the glands on the plant were reduced significantly.

Breeding, introgression and inheritance of delayed gland morphogenesis trait fromGosspium bickii into upland cotton germplasm

A tri-specific hybrid with delayed pigment gland morphogenesis was obtained by crossing the amphidiploid of (G. arboreum X G. bickii) F1 and an upland cotton germplasm with pigment gland genotype of Gl2Gl2gl3gl3. The tri-speciflc hybrid was a typical interspecific hybrid with high sterile, and the chromosome configuration at meiosis MI of PMC was 2n = 52 = 41.04 I + 4.54 II + 0.57III + 0.04. The crossover value of bivalent was 1.19. Two fertile plants with objective character were obtained in BC8 population by continuously backcrossing with Gl2Gl2gl3gl3 as recurrent parent to the tri-specific hybrid, and a new upland cotton germplasm, named ABH-0318, with delayed pigment gland morphogenesis trait was developed through selfing and screening. The pigment gland trait of ABH-0318 was stable, and there were almost no pigment glands observed in the dormant seeds, although there were a few pigment glands confined to cotyledon edges, and the gossypol content in the dormant seeds was 0.017% only, being a typical low gossypol cotton type. However, a large quantity of pigment glands emerged in cotyledons and other main organs of plant after seed germination, and the gossypol contents in the upper parts of the plant were similar to that of ordinary glanded cotton types. Genetic analysis demonstrated that the delayed pigment gland morphogenesis trait of this germplasm was controlled by the interaction of the genes located in two pigment gland loci, Gl2and Gl3. Among them, the gene located in locus of Gl2, derived fromGbickii, was dominance to upland cotton pigment gland alleles, Gl2 and gl2, but was recessive epistatic to another glanded gene Gl3 which was named Gl2 b temporarily. While the gene located in the locus of Gl3 was a recessive gene come from upland cotton.

Marker-assisted selection for the wide-spectrum resistance to root-knot nematodes conferred by the Ma gene from Myrobalan plum (Prunus cerasifera) in interspecific Prunus material

Prunus species express a more or less wide spectrum of resistance to root-knot nematodes (RKN) of the genus Meloidogyne. Among them, sources from Myrobalan plum (P. cerasifera) control all major and minor RKN species tested. In this outbreeding species, the clones P.2175 and P.2980 are heterozygous for the Ma single dominant gene and carry the alleles Ma1 and Ma3, respectively. Each allele confers a high-level resistance to the predominant RKN, M. arenaria, M. incognita and M. javanica and to the Florida isolate of an unknown Meloidogyne sp. which overcomes the resistance from peach and almond sources. The polymorphism of two coupling-phase SCAR markers tightly linked to Ma, SCAL19690 and SCAFLP2202, was evaluated within diverse diploid Prunus accessions. This material belongs to the subgenera Prunophora (Myrobalan and apricot) or Amygdalus (peach, almond and almond-peach) and includes the RKN resistance sources ‘Nemared’, ‘Alnem 1’ and ‘GF.557’. The alleles SCAL19690 and SCAFLP2202 were not present in three apricot cultivars (‘Moniqui’, ‘Luizet’ and ‘Stark Early Orange’) representative of the genetic diversity of this species and they segregated in an interspecific cross between P.2980 and apricot. These results suggest that apricot, reported as resistant to M. arenaria, M. incognita and M. javanica, and the Myrobalan plum might possess two different resistance systems. SCAL19690 and SCAFLP2202 were also absent from all tested Amygdalus material, whatever its resistance to RKN. Eight Myrobalan×Amygdalus segregating progenies including bispecific (P.2175 or P.2980×peach or almond) and trispecific (P.2175 or P.2980×almond-peach) hybrids were tested with the Florida isolate to identify individuals carrying the Ma resistance alleles. Both SCARs were then evaluated for segregation in these progenies to develop marker-assisted selection of Prunus interspecific rootstocks. SCAL19690 and SCAFLP2202 could be clearly detected and their tight linkage to Ma1 and Ma3 was confirmed. Consequently these SCARs appear to be powerful tools to screen for RKN resistance conferred by the Ma gene. They should also facilitate marker-assisted pyramiding of Ma with other resistance genes from the Amygdalus subgenus or from the botanically-related Armeniaca section.

Effect of nitrogen and Azospirillum inoculation on growth and green forage yield of Pennisetum trispecific hybrid

Inoculation of Azospirillum significantly influenced the leaf : stem ratio (LSR) of Pennisetum trispecifio hybrid (P. typoides x P. purpureum x P. squmulatum), but its effect on number of tillers was not consistent. Application of nitrogen did not significantly influence the number of tillers,LSR and green forage yield during the first year. Inoculation of Azospirillum strain ACD 20 recorded significantly higher green forage yield than ACD 15 and the control. Theeincrease in green forage yield owing to inoculation of strain ACD 20 over ACD 15 was 18% and over the control was 25%. Azospirilium strain ACD 20 inoculation could give an equivalent green forage yield as given by application of 25 kg Wtha. The benefit : c s t ratio was maximum (2.35) when Azospirillum strain ACD 20 inoculated to .= was Pennisetum trispecific hybrid, followed by application of 75 kg Nlha (2.09) and 25 Kg Nlha (2.07).

Effect of planting geometry and cutting management on productivity, quality and economics of mixed pasture under rainfed conditions

A field experiment was conducted on sandy-loam soil for 5 years (1997-98 to 2001-02) at Jhansi, Uttar Pradesh, to study the effect of planting pattern and harvest intervals on yield, quality and monetary return of pas- ture under rainfed semi-arid conditions. Four methods of planting geometry of grasses, viz. Pennisetum trispecific hybrid [(Pennisetum americanum x Pennisetum purpureum ) x Pennisetum squamulatum], Pennisetum pedicellatum, Chrysopogon fulvus and Andropogon gayanus and legumes, viz. Stylosanthes hamata, Stylosanthes scabra, Macroptillium atropurpureum, Clitoria ternatea and Atylosia scarabaoides (1 : I 4 0 cm, 1 :2- 50 cm, 1 :I-75 cm and 1 :2-75 cm apart), and four harvesting intervals (45, 70, 95 and 120 days) in mixed pastures were studied. Planting of grasses and legumes in 1:l row ratio at 50 cm distance resulted in significantly higher green forage (22.0 tlha) and dry-matter yield (5.41 tlha) compared with 1.2 row ratio at 75 cm distance (green for- age 19.31 tlha and dry matter 4.61 tlha) during all the 5 years. Total green forage (23.2 tiha) and dry-matter yield (5.62 tlha) was also significantly increased with the harvesting of pasture at 70-day interval than other harvest in- tervals. The highest net returns (Rs 5,7171ha) and benefit : cost ratio (0.76) were obtained in 1 :I row ratio at 50 cm distance. Among harvesting treatments, highest net returns (Rs 6,793lha) and benefit : cost ratio (1.95) were achieved with 70-day harvest interval. The significant improvement in crude-protein content (grasses 6.55% and legumes 11.4%) and reduction in neutral detergent fibre (grasses 67.87% and legumes 52.81%) and acid deter- gent fibre (grasses 47.72% and legumes 36.69%) in forage was recorded in 1 :2 row ratio of grass-legume inter- cropping than 1 :I row ratio at 75 cm distance. Harvesting of pasture at 45 days interval resulted in significantly higher crude protein content (grasses 6.98% and legumes 11.35%) and lower neutral detergent fibre (grasses 64.25% and legumes 48.18%), acid detergent fibre (grasses 45.26% and legumes 33.42%) compared with 70 days, 95 days and 120 days harvest intervals, respectively in all the 5 years.

Cytogenetics of the ‘glandless‐seed and glanded‐plant’ trait from Gossypium sturtianum Willis introgressed into upland cotton (Gossypium hirsutum L.)

AbstractIn order to introgress the ‘glandless‐seed and glanded‐plant’ trait from Gossypium sturtianum Willis (2n= 2x= 26, C1 genome) into the cultivated upland cotton Gossypium hirsutum L. (2n= Ax= 52 (AD), genome), two trispecific hybrids have been created using either Gossypium thurberi Torado (2n= 2x= 26, D1 genome) or Gossypium raimondii Ulbrich (2n= 2x= 26, D5 genome) as bridge species. The cross of both trispecific hybrids by G. hirsutum produced the first backcross progenies (BCl). Cytogenetic analysis showed that the trispecific hybrids had 52 chromosomes, their chromosome configurations at metaphase I (Ml) being 15.071 + 15.3411 + 0.93III + 0.69IV + 0.26VI in G. thurberi×G. sturtianum×G. hirsutum (TSH) and 14.421 + 17.0311 + 0.82III + 0.15IV + 0.07VI in G. hirsutum × G. raimondii ×. G. sturtianum (HRS), respectively. Among six BCl plants analysed, the only plant expressing the ‘glandless‐seed and glanded‐plant’ trait had 52 chromosomes and a meiotic configuration of 5.261 + 20.61II + 0.69III + 0.77IV at MI. Pollen fertility was 2.90% in TSH, 8.97% in HRS, and ranged from 0% to 40.28% in the BCl progenies. The introgressed BCl plant is perennial in growth habit. It can be used in breeding programmes aiming at the introgression of the ‘glandless‐seed and glanded‐plant’ trait into a cultivar of upland cotton.

Intersectional cottonwood hybrids are particularly susceptible to the poplar bud gall mite

The occurrence of hybrid breakdown, the poor performance of certain hybrids, was investigated in cottonwoods (Populus) with respect to susceptibility to the poplar bud gall mite, Aceria parapopuli. The abundance of mite galls was investigated for all 352 cottonwoods on an island at Lethbridge, Alberta, where a natural trispecific hybrid swarm involves the narrowleaf cottonwood (Populus angustifolia) and the balsam poplar (Populus balsamifera) of section Tacamahaca and the prairie cottonwood (Populus deltides) of section Aigeiros. There, 78% of the intersectional hybrids (i.e., P. deltoides × P. angustifolia or P. balsamifera), 56% of the intrasectional (P. angustifolia × P. balsamifera) hybrids, and 36% of the single-species trees displayed some galls. Nine percent were heavily infested, and these were almost all intersectional hybrids. At four other riparian sites in British Columbia and Alberta with only single species or the two Tacamahaca cottonwoods, very few galls were observed and no trees were severely infested. Conversely, artificially planted intersectional hybrids near all sites displayed severe infestations, confirming the occurrence of mites throughout the region and the susceptibility of intersectional hybrids. The susceptibility to pests probably hinders growth and reproduction and thus disfavors the intersectional hybrids. Since hybrid poplars are widely planted for horticultural or silvicultural applications, this study suggests that future selections should consider the vulnerability of hybrids and especially intersectional hybrids to insect pests. Key words: Populus, insect pests, cottonwoods, galls, hybrids, riparian vegetation.

A Diagnostic Test to Confirm Interspecific Allium Hybrids Using Random Amplified Polymorphic DNA from Crude Leaf DNA Extracts.

A crude extraction procedure for DNA was modified and used for small leaf samples (2-4 mg) in Allium. Six random decamers (OPD 5, 7, 14, 15, 18 and 19) generated characteristic random amplified polymorphic DNA (RAPD) profiles from leaf DNA of Allium tuberosum Rottl. ex Spreng. 'Tender pole' obtained using a crude micro extraction process These RAPD profiles were roughly similar to those of DNA purified using a sodium dodecyl sulfate (SDS) extraction procedure.Crude extracts of leaf DNA were prepared from three accessions of A. tuberosum 'Tender pole', 'five 'Yoshitake hybrids' (A. chinense G. Don × A. thunbergii G. Don) and seven putative trispecific hybrids between these two groups. DNA amplification with four random decamers (OPD 14, 15, 18 and 19) by polymerase chain reaction produced a total of 186 bands : 49 bands were found only in the RAPD profiles of the putative hybrid and the corresponding male parent (M bands), whereas 58 bands were found in both female parent and trispecific hybrid plants (F bands). One of the seven putative hybrids had no M band, indicating that it had no relationship to its putative male parent and that it may have been the product of an unwanted pollination.